JP5158253B2 - Brake control device - Google Patents

Abstract

In a brake control apparatus 20, an isolation valve 60 is provided in a main flow channel 45 that brings a first hydraulic pressure circuit and a second hydraulic pressure circuit into communication with each other. When a problem detection unit detects a problem related to brake fluid pressure, a control unit brings the isolation valve 60 into a closed state. A leakage prevention unit performs a leakage prevention process for preventing the brake fluid in the first hydraulic pressure circuit from flowing into the second hydraulic pressure circuit after the isolation valve 60 is brought into the closed state. The leakage prevention unit performs the leakage prevention process by bringing a master cut valve 64 into a closed state.

Description

  The present invention relates to a brake control device that controls braking force applied to wheels provided in a vehicle.

A brake control device is known that includes a hydraulic circuit that supplies hydraulic pressure to a wheel cylinder from a manual hydraulic pressure source, and a hydraulic circuit that supplies hydraulic pressure to the wheel cylinder from an accumulator (see, for example, Patent Document 1). This brake control device operates the pressure control mechanism in the absence of a brake operation, generates differential pressure on both sides of the separation valve that separates the hydraulic circuit from the manual hydraulic pressure source into two systems, and changes in differential pressure A brake ECU for determining whether or not there is a leakage abnormality in the separation valve based on the above.
JP 2007-131247 A

  In a vehicle equipped with an electric motor as a travel drive source such as a hybrid vehicle or an electric vehicle, so-called regenerative coordination in which a required braking force is generated by using both a braking force due to regeneration and a braking force due to hydraulic pressure during braking. Control may be performed. Since part of the kinetic energy during traveling is recovered as electric energy during braking by regenerative braking, regenerative cooperative control contributes to an improvement in the fuel consumption of the vehicle. In order to further improve the fuel consumption of the vehicle, it is desirable to start the regenerative cooperative control immediately after the vehicle driving source is started.

  In the regenerative cooperative control, the hydraulic pressure transmitted to the wheel cylinder of each wheel by the brake control device is adjusted in consideration of the braking force due to regeneration, not the hydraulic pressure pressurized according to the operation amount of the brake operation member. Hydraulic pressure. When an abnormality is detected in the mechanism for adjusting the hydraulic pressure, the regenerative cooperative control is stopped, and the hydraulic pressure pressurized in accordance with the brake operation amount by the manual hydraulic pressure source such as the master cylinder remains as it is. Is transmitted to. By configuring the hydraulic pressure transmission circuit from the manual hydraulic pressure source to each wheel cylinder so that it can be separated into two systems by the separation valve, if another failure occurs, for example, one system will leak from the piping Even in this case, the normal system can be separated from the faulty system by the separation valve, and the braking force can be generated by the normal system. Thus, it is preferable from the viewpoint of fail-safe that it is possible to generate a braking force even if double failures occur.

  However, when a normally closed electromagnetic control valve is employed as such a separation valve, the separation valve will be opened if a differential pressure greater than the spring force urging in the closing direction occurs before and after that. . When fluid leakage occurs due to a piping failure in one system, the fluid pressure in that system is close to 0, but when the brake pedal is depressed in that state, the fluid pressure in the other normal system increases. . If the differential pressure generated before and after the separation valve becomes larger than the spring force at this time, the separation valve is opened and hydraulic fluid (hereinafter also referred to as “brake fluid”) flows from the normal system into the system where the failure occurred. As a result, the brake fluid in the normal system is reduced.

  Therefore, it is important that the separation valve can normally separate the systems, and it is preferable to suppress the inflow of the hydraulic fluid from the normal system to the system in which the abnormality has occurred. Appropriate brake control can be realized by appropriately separating the systems.

  Therefore, an object of the present invention is to provide a brake control device that can appropriately separate two systems, that is, a hydraulic circuit.

  In order to solve the above problems, a brake control device according to an aspect of the present invention includes a first wheel cylinder for applying a braking force to a first wheel, and a second wheel different from the first wheel. A second wheel cylinder for applying a braking force; a first hydraulic circuit for supplying brake fluid from the reservoir to the first wheel cylinder; and a second hydraulic cylinder for supplying brake fluid from the reservoir to the second wheel cylinder. Two fluid pressure circuits, a separation valve provided in a main flow path communicating the first fluid pressure circuit and the second fluid pressure circuit, an abnormality detection means for detecting an abnormality relating to brake fluid pressure, and a brake fluid by the abnormality detection means When an abnormality relating to pressure is detected, the control means for closing the separation valve, and after the separation valve is closed by the control means, the brake fluid in the first hydraulic pressure circuit is And a leakage suppression means for performing the suppressing leakage suppression processing to flow into the hydraulic circuit. According to this aspect, it is possible to maintain the brake fluid amount in the first hydraulic circuit by executing the leakage suppression process after the separation valve is closed.

  The leak suppression unit may execute the leak suppression process by closing the control valve. The leakage suppression means can suppress the inflow of brake fluid from the first hydraulic pressure circuit to the second hydraulic pressure circuit by closing the control valve and preventing the supply of hydraulic pressure from the hydraulic pressure source. The control valve may be provided in the middle of the reservoir and the separation valve in the first hydraulic circuit. The separation valve may be a differential pressure valve that opens when the differential pressure before and after the separation valve becomes equal to or greater than a predetermined value P1.

  The brake control device may further include first fluid pressure detecting means for detecting the brake fluid pressure of the first hydraulic pressure circuit, and second fluid pressure detecting means for detecting the brake fluid pressure of the second hydraulic pressure circuit. Good. The leak suppression unit executes the leak suppression process when the differential pressure derived from the detection value of the first fluid pressure detection unit and the detection value of the second fluid pressure detection unit exceeds a predetermined value P2 smaller than the predetermined value P1. May be. As a result, it is possible to avoid a situation in which brake fluid flows from the first hydraulic pressure circuit into the second hydraulic pressure circuit via the separation valve.

  The brake control device includes: a first determination unit that determines that the brake fluid amount in the reservoir has decreased below a reference value; a second fluid pressure detection unit that detects a brake fluid pressure in the second hydraulic circuit; From the third fluid pressure detecting means for detecting the brake fluid pressure and the brake fluid pressure of the second hydraulic circuit being lower than the predetermined value P3, or the brake fluid pressure in the accumulator flow path being lower than the predetermined value P4, You may further provide the 2nd determination means which determines pressure drop abnormality, and the leak detection means which detects the brake fluid leak to the exterior. The leak detecting means determines that the brake fluid amount has fallen below the reference value by the first determining means, and if the second determining means determines that the pressure drop is abnormal, the leak detecting means Brake fluid leakage may be detected. As a result, it is possible to accurately detect brake fluid leakage.

  The second determination means is that the state in which the brake fluid pressure in the second hydraulic circuit is lower than the predetermined value P3 continues for the time Ta, or the state in which the brake fluid pressure in the accumulator passage is lower than the predetermined value P4 continues for the time Tb. Therefore, a pressure drop abnormality may be determined. As a result, it is possible to accurately determine a pressure drop abnormality.

  The brake control device performs a system check at the time of start-up, and the second determination means immediately after the system check ends that the state in which the brake fluid pressure of the second hydraulic circuit is lower than the predetermined value P3 is from the time Ta. The pressure drop abnormality may be determined because it has continued for a short time or because the state in which the brake fluid pressure in the accumulator flow path is lower than the predetermined value P4 has continued for a time shorter than the time Tb. As a result, immediately after the system check, it is possible to determine a pressure drop abnormality earlier than usual.

  The leak suppression unit may execute the leak suppression process when the brake fluid pressure of the first hydraulic circuit exceeds a predetermined value P5. This makes it possible to maintain the brake fluid pressure necessary to ensure the braking force during the execution of the leak suppression process.

  The leak suppression unit may temporarily stop the leak suppression process when the brake fluid pressure of the first hydraulic pressure circuit falls below a predetermined value P6 during the execution of the leak suppression process. Thereby, it becomes possible to raise the brake fluid pressure of a 1st hydraulic circuit.

  The brake control device may further include a pressurization state determination unit that determines the pressurization state of the first hydraulic circuit. The leakage suppression means may execute a leakage suppression process when it is determined by the pressurization state determination means that the first hydraulic circuit is in a state of being pressurized. As a result, the leakage suppression process can be executed in a situation where brake fluid leakage can occur. The pressurization status determination means may determine the pressurization status from the output of the brake pedal stroke detection means. If it is determined by the pressurization state determination means that the pedal stroke amount exceeds the predetermined amount L1, the leakage suppression means may execute a leakage suppression process. Thereby, for example, it can be estimated that the brake pedal has been depressed with a high depression force, and the leakage suppression process can be executed.

  The leakage suppression unit may stop the leakage suppression process being executed when it is determined by the pressurization state determination unit that the first hydraulic circuit is not pressurized. Thereby, under the situation where the leak suppression process is unnecessary, the leak suppression process can be stopped early.

  The pressurization state determination means stores the pedal stroke amount L2 at the time when the leakage suppression process is executed, and the pedal stroke amounts are L2−Lr (Lr is a predetermined amount) and a predetermined amount L3 (L3 <L1). When the value falls below the smaller one, the leakage suppression unit may stop the leakage suppression process being executed. Thereby, a smooth brake return feeling can be given to the driver.

  The brake control device may further include an abnormality determination unit that determines an output abnormality of a brake pedal stroke detection unit or a brake fluid pressure detection unit. When the abnormality determination unit determines that the output is abnormal, the leakage suppression unit may stop the leakage suppression process being executed. Further, when it is determined by the first determination means that the brake fluid amount has become equal to or greater than the reference value, the leakage suppression means may stop the leakage suppression process being executed. Further, when the brake fluid pressure in the accumulator flow path exceeds the predetermined value P7, the leakage suppression means may stop the leakage suppression process being executed. Further, when the vehicle is being inspected or being maintained, the leakage suppression unit may prohibit execution of the leakage suppression process.

  According to the present invention, it is possible to provide a brake control device that can appropriately separate two hydraulic circuits.

It is a figure showing a brake control device concerning an embodiment of the present invention. It is a flowchart for demonstrating the control processing in regeneration cooperation control mode. It is a figure which shows the control hydraulic pressure which acts on a wheel cylinder after a braking request | requirement. It is a flowchart for demonstrating control hydraulic pressure response abnormality determination process S22. It is a figure which shows the structure of brake ECU which determines a brake mode. It is a figure which shows the internal structure of a reservoir, and a connection structure with piping. It is a flowchart for demonstrating the basic control of the leak suppression process of this embodiment. It is a figure which shows the structure of brake ECU which performs a leak suppression process. It is a flowchart for demonstrating the detail of control of the leak suppression process of this embodiment. It is a figure which shows the flowchart for demonstrating determination process S112 of piping failure. It is a figure which shows the flowchart for demonstrating determination process S134 of a pressure drop abnormality. It is a figure which shows the flowchart which added time conditions to determination process S134 of the pressure drop abnormality shown in FIG. It is a figure which shows a process when a piping failure has generate | occur | produced at the time of ECU starting, and a transition of a state value. It is a flowchart for demonstrating driving mode determination process S120. FIG. 10 is a diagram showing transitions of state values and state quantities when other conditions are satisfied and leakage suppression processing is executed after the brake fluid pressure Pfr of the first hydraulic pressure circuit exceeds P5 in S116 of FIG. 9. is there. It is a flowchart for demonstrating the temporary stop process of a leak suppression process. It is a figure which shows the transition of a state value and state quantity when the brake fluid pressure Pfr of a 1st hydraulic circuit is maintained between P6 and P5. It is a flowchart for demonstrating an example of the cancellation process of a leak suppression process. It is a flowchart for demonstrating another example of the cancellation process of a leak suppression process. It is a flowchart for demonstrating another example of the cancellation process of a leak suppression process. It is a flowchart for demonstrating another example of the cancellation process of a leak suppression process. It is the flowchart which improved the cancellation process of the leak suppression process shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Master cylinder unit, 20 ... Brake control apparatus, 23 ... Wheel cylinder, 24 ... Brake pedal, 25 ... Stroke sensor, 30 ... Power hydraulic pressure source, 31 ... Hydraulic booster, 32 ... master cylinder, 33 ... regulator, 34 ... reservoir, 35 ... accumulator, 37 ... master piping, 38 ... regulator piping, 39 ... accumulator piping, 40 ... hydraulic actuator, 45a ... first flow path, 45b ... second flow path, 55 ... reservoir flow path, 56 ... ABS pressure reducing valve, 60 ... separation valve, 61 ... Master flow path, 62 ... Regulator flow path, 63 ... Accumulator flow path, 64 ... Master cut valve, 65 ... Regulator cut valve, 66 ... Pressure increase linear control Valve: 67 ... Pressure reducing linear control valve, 68 ... Simulator cut valve, 70 ... Brake ECU, 71 ... Regulator pressure sensor, 72 ... Accumulator pressure sensor, 73 ... Control pressure sensor, 77 ... reservoir piping, 78 ... pump piping, 79 ... master chamber, 80 ... regulator chamber, 86 ... decrease determination line, 87 ... reservoir amount decrease detection switch, 100 ... Abnormality detection unit, 102 ... brake mode control unit, 108 ... HB mode determination unit, 110 ... condition determination unit, 112 ... storage amount determination unit, 114 ... disconnection determination unit, 116 ... Pressure drop abnormality determination unit 118 ... Pipe failure determination unit 120 ... Differential pressure determination unit 122 ... Hydraulic pressure determination unit 124 ... Pressure condition determination unit 126 ... Running Mode determination unit, 12 ... abnormality determination unit, 150 ... leakage suppression unit.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a brake control device 20 according to an embodiment of the present invention. A brake control device 20 shown in the figure constitutes an electronically controlled brake system (ECB) for a vehicle, and controls braking force applied to four wheels provided on the vehicle. The brake control device 20 according to the present embodiment is mounted on, for example, a hybrid vehicle that includes an electric motor and an internal combustion engine as a travel drive source. In such a hybrid vehicle, each of regenerative braking that brakes the vehicle by regenerating kinetic energy of the vehicle into electric energy and hydraulic braking by the brake control device 20 can be used for braking the vehicle. The vehicle in the present embodiment can execute brake regenerative cooperative control that generates a desired braking force by using both the regenerative braking and the hydraulic braking together.

  As shown in FIG. 1, the brake control device 20 includes disc brake units 21FR, 21FL, 21RR and 21RL as a braking force applying mechanism provided for each wheel (not shown), a master cylinder unit 10, a power A hydraulic pressure source 30 and a hydraulic actuator 40 are included.

  Disc brake units 21FR, 21FL, 21RR, and 21RL apply braking force to the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel of the vehicle, respectively. The master cylinder unit 10 as a manual hydraulic pressure source sends brake fluid pressurized according to the amount of operation of the brake pedal 24 as a brake operation member by the driver to the disc brake units 21FR to 21RL. The power hydraulic pressure source 30 can send the brake fluid as the working fluid pressurized by the power supply to the disc brake units 21FR to 21RL independently from the operation of the brake pedal 24 by the driver. is there. The hydraulic actuator 40 appropriately adjusts the hydraulic pressure of the brake fluid supplied from the power hydraulic pressure source 30 or the master cylinder unit 10 and sends it to the disc brake units 21FR to 21RL. Thereby, the braking force with respect to each wheel by hydraulic braking is adjusted. In the present embodiment, a wheel cylinder pressure control system is configured including the power hydraulic pressure source 30 and the hydraulic actuator 40.

  Each of the disc brake units 21FR to 21RL, the master cylinder unit 10, the power hydraulic pressure source 30, and the hydraulic actuator 40 will be described in more detail below. Each of the disc brake units 21FR to 21RL includes a brake disc 22 and wheel cylinders 23FR to 23RL incorporated in the brake caliper, respectively. The wheel cylinders 23FR to 23RL are connected to the hydraulic actuator 40 via different fluid passages. Hereinafter, the wheel cylinders 23FR to 23RL are collectively referred to as “wheel cylinders 23” as appropriate. Thus, the hydraulic actuator 40 switches the flow path of the brake fluid supplied from at least one of the master cylinder unit 10 and the power hydraulic pressure source 30, and controls the hydraulic pressure of the brake fluid transmitted to the wheel cylinder 23. Functions as a pressure control mechanism. Although details will be described later, the hydraulic actuator 40 includes a plurality of control valves and hydraulic pressure sensors for switching the flow path and blocking the flow path.

  In the disc brake units 21FR to 21RL, when brake fluid is supplied to the wheel cylinder 23 from the hydraulic actuator 40, a brake pad as a friction member is pressed against the brake disc 22 that rotates together with the wheel. Thereby, a braking force is applied to each wheel. In the present embodiment, the disc brake units 21FR to 21RL are used, but other braking force applying mechanisms including a wheel cylinder such as a drum brake may be used.

  The master cylinder unit 10 is a master cylinder with a hydraulic booster in this embodiment, and includes a hydraulic booster 31, a master cylinder 32, a regulator 33, and a reservoir 34. The hydraulic booster 31 is coupled to the brake pedal 24, amplifies the pedal effort applied to the brake pedal 24, transmits the pedal depression force to the master cylinder 32, and pressurizes the brake fluid. When the brake fluid is supplied from the power hydraulic pressure source 30 to the hydraulic pressure booster 31 via the regulator 33, the pedal effort is amplified. The master cylinder 32 generates a master cylinder pressure having a predetermined boost ratio with respect to the pedal effort.

  A reservoir 34 for storing brake fluid is disposed above the master cylinder 32 and the regulator 33. The master cylinder 32 communicates with the reservoir 34 when the depression of the brake pedal 24 is released. On the other hand, the regulator 33 communicates with both the reservoir 34 and the accumulator 35 of the power hydraulic pressure source 30, and the reservoir 34 is a low pressure source, the accumulator 35 is a high pressure source, and a predetermined amount with respect to the master cylinder pressure. Produces a hydraulic pressure ratio. Hereinafter, the hydraulic pressure in the regulator 33 is appropriately referred to as “regulator pressure”.

  The power hydraulic pressure source 30 includes an accumulator 35 and a pump 36. The accumulator 35 converts the pressure energy of the brake fluid boosted by the pump 36 into the pressure energy of an enclosed gas such as nitrogen, for example, about 14 to 22 MPa and stores it. The pump 36 has a motor 36 a as a drive source, and its suction port is connected to the reservoir 34 via a pump pipe 78, while its discharge port is connected to the accumulator 35. The accumulator 35 is also connected to a relief valve 35 a provided in the master cylinder unit 10. When the pressure of the brake fluid in the accumulator 35 increases abnormally to about 25 MPa, for example, the relief valve 35 a is opened, and the high-pressure brake fluid is returned to the reservoir 34.

  As described above, the brake control device 20 includes the master cylinder 32, the regulator 33, and the accumulator 35 as a supply source of brake fluid to the wheel cylinder 23. A master pipe 37 is connected to the master cylinder 32, a regulator pipe 38 is connected to the regulator 33, and an accumulator pipe 39 is connected to the accumulator 35. These master pipe 37, regulator pipe 38 and accumulator pipe 39 are each connected to a hydraulic actuator 40.

  The hydraulic actuator 40 includes an actuator block in which a plurality of flow paths are formed as a hydraulic circuit, and a plurality of electromagnetic control valves. The flow paths formed in the actuator block include individual flow paths 41, 42, 43 and 44 and a main flow path 45. The individual flow paths 41 to 44 are respectively branched from the main flow path 45 and connected to the wheel cylinders 23FR, 23FL, 23RR, 23RL of the corresponding disc brake units 21FR, 21FL, 21RR, 21RL. Thereby, each wheel cylinder 23 can communicate with the main flow path 45.

  In addition, ABS holding valves 51, 52, 53 and 54 are provided in the middle of the individual flow paths 41, 42, 43 and 44. Each of the ABS holding valves 51 to 54 has a solenoid and a spring that are ON / OFF controlled, and both are normally open electromagnetic control valves that are opened when the solenoid is in a non-energized state. Each of the ABS holding valves 51 to 54 in the opened state can distribute the brake fluid in both directions. That is, the brake fluid can flow from the main flow path 45 to the wheel cylinder 23, and conversely, the brake fluid can also flow from the wheel cylinder 23 to the main flow path 45. When the solenoid is energized and the ABS holding valves 51 to 54 are closed, the flow of brake fluid in the individual flow paths 41 to 44 is blocked.

  Further, the wheel cylinder 23 is connected to the reservoir channel 55 via pressure reducing channels 46, 47, 48 and 49 connected to the individual channels 41 to 44, respectively. ABS decompression valves 56, 57, 58 and 59 are provided in the middle of the decompression channels 46, 47, 48 and 49. Each of the ABS pressure reducing valves 56 to 59 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the ABS pressure reducing valves 56 to 59 are closed, the flow of brake fluid in the pressure reducing flow paths 46 to 49 is blocked. When the solenoid is energized and the ABS pressure reducing valves 56 to 59 are opened, the brake fluid is allowed to flow through the pressure reducing flow paths 46 to 49, and the brake fluid flows from the wheel cylinder 23 to the pressure reducing flow paths 46 to 49 and It returns to the reservoir 34 via the reservoir channel 55. The reservoir channel 55 is connected to the reservoir 34 of the master cylinder unit 10 via a reservoir pipe 77. As described above, the reservoir channel 55 and the reservoir pipe 77 function as a circulation channel formed to circulate the brake fluid from the wheel cylinder 23 to the reservoir 34. The circulating flow path constitutes a drain circuit between the ABS pressure reducing valves 56 to 59 and the reservoir 34. Since the reservoir 34 is connected to the drain circuit, and the reservoir 34 is open to the atmosphere, the brake fluid pressure in the circulation flow path is equal to the atmospheric pressure while the ABS pressure reducing valves 56 to 59 are closed. Become.

  The main channel 45 has a separation valve 60 in the middle. By this separation valve 60, the main channel 45 is divided into a first channel 45 a connected to the individual channels 41 and 42 and a second channel 45 b connected to the individual channels 43 and 44. The first flow path 45a is connected to the front wheel side wheel cylinders 23FR and 23FL via the individual flow paths 41 and 42, and the second flow path 45b is connected to the rear wheel side wheel cylinder via the individual flow paths 43 and 44. Connected to 23RR and 23RL.

  The separation valve 60 has a solenoid and a spring that are ON / OFF controlled, and is a normally closed electromagnetic control valve that is closed when the solenoid is in a non-energized state. When the separation valve 60 is in the closed state, the flow of brake fluid in the main flow path 45 is blocked. When the solenoid is energized and the separation valve 60 is opened, the brake fluid can be circulated bidirectionally between the first flow path 45a and the second flow path 45b. That is, the separation valve 60 can control the flow of brake fluid between the first flow path 45a and the second flow path 45b.

  In the hydraulic actuator 40, a master channel 61 and a regulator channel 62 communicating with the main channel 45 are formed. More specifically, the master channel 61 is connected to the first channel 45 a of the main channel 45, and the regulator channel 62 is connected to the second channel 45 b of the main channel 45. The master channel 61 is connected to a master pipe 37 that communicates with the master cylinder 32. The regulator channel 62 is connected to a regulator pipe 38 that communicates with the regulator 33.

  The master channel 61 has a master cut valve 64 in the middle. The master cut valve 64 has a solenoid that is ON / OFF controlled and a spring, and is a normally open electromagnetic control valve that is opened when the solenoid is in a non-energized state. The master cut valve 64 in the opened state can cause the brake fluid to flow in both directions between the master cylinder 32 and the first flow path 45 a of the main flow path 45. When the solenoid is energized and the master cut valve 64 is closed, the flow of brake fluid in the master channel 61 is blocked.

  A stroke simulator 69 is connected to the master channel 61 via a simulator cut valve 68 on the upstream side of the master cut valve 64. That is, the simulator cut valve 68 is provided in a flow path connecting the master cylinder 32 and the stroke simulator 69. The simulator cut valve 68 is a normally closed electromagnetic control valve that has a solenoid and a spring that are ON / OFF controlled and is closed when the solenoid is in a non-energized state. When the simulator cut valve 68 is closed, the flow of brake fluid between the master flow path 61 and the stroke simulator 69 is blocked. When the solenoid is energized and the simulator cut valve 68 is opened, the brake fluid can be circulated bidirectionally between the master cylinder 32 and the stroke simulator 69.

  The stroke simulator 69 includes a plurality of pistons and springs, and uses the brake fluid sent from the master cylinder unit 10 to generate a reaction force according to the pedaling force of the brake pedal 24 by the driver when the simulator cut valve 68 is opened. Create. As the stroke simulator 69, in order to improve the feeling of brake operation by the driver, it is preferable to employ one having multi-stage spring characteristics, and the stroke simulator 69 of this embodiment has multi-stage spring characteristics.

  The regulator flow path 62 has a regulator cut valve 65 in the middle. The regulator cut valve 65 also has a solenoid and a spring that are ON / OFF controlled, and is a normally open electromagnetic control valve that is opened when the solenoid is in a non-energized state. The regulator cut valve 65 that has been opened can cause the brake fluid to flow in both directions between the regulator 33 and the second flow path 45 b of the main flow path 45. When the solenoid is energized and the regulator cut valve 65 is closed, the flow of brake fluid in the regulator flow path 62 is blocked.

  In the present embodiment, the master cylinder 32 of the master cylinder unit 10 communicates with the wheel cylinders 23FR and 23FL on the front wheel side by a first hydraulic circuit that includes the following elements. The first hydraulic circuit is configured to transmit the hydraulic pressure of the brake fluid in the master cylinder unit 10 to the wheel cylinders 23FR and 23FL on the front wheel side, and the first flow path 45a of the master pipe 37, the master flow path 61, and the main flow path 45. , Including individual flow paths 41 and 42, and the like. The master pipe 37, the master channel 61, the first channel 45a of the main channel 45, and the individual channels 41 and 42 form a pressure increasing channel in the first hydraulic circuit. The hydraulic booster 31 and the regulator 33 of the master cylinder unit 10 are communicated with the wheel cylinders 23RR and 23RL on the rear wheel side by a second hydraulic circuit including the following elements. The second hydraulic pressure circuit is configured to transmit the hydraulic pressure of the brake fluid in the master cylinder unit 10 to the wheel cylinders 23RR and 23RL on the rear wheel side, and the second flow path of the regulator pipe 38, the regulator flow path 62, and the main flow path 45. 45b, individual flow paths 43 and 44, and the like. The regulator pipe 38, the regulator channel 62, the second channel 45b of the main channel 45, and the individual channels 43 and 44 form a pressure increasing channel in the second hydraulic circuit.

  Therefore, the hydraulic pressure in the master cylinder unit 10 pressurized according to the brake operation amount by the driver is transmitted to the wheel cylinders 23FR and 23FL on the front wheel side through the first hydraulic pressure circuit. Further, the hydraulic pressure in the master cylinder unit 10 is transmitted to the wheel cylinders 23RR and 23RL on the rear wheel side via the second hydraulic pressure circuit. Thereby, the braking force according to the amount of brake operation of the driver can be generated in each wheel cylinder 23. That is, each wheel cylinder 23 can apply braking force to the wheels by receiving the supply of brake fluid.

  In addition to the master channel 61 and the regulator channel 62, an accumulator channel 63 is also formed in the hydraulic actuator. One end of the accumulator channel 63 is connected to the second channel 45 b of the main channel 45, and the other end is connected to an accumulator pipe 39 that communicates with the accumulator 35.

  The accumulator flow path 63 has a pressure-increasing linear control valve 66 in the middle. Further, the accumulator channel 63 and the second channel 45 b of the main channel 45 are connected to the reservoir channel 55 via the pressure-reducing linear control valve 67. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 each have a linear solenoid and a spring, and both are normally closed electromagnetic control valves that are closed when the solenoid is in a non-energized state. Therefore, unlike the on / off control valves such as the master cut valve 64 and the regulator cut valve 65 that perform the on / off operation, the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 correspond to the currents supplied to the respective solenoids. The opening of the valve is adjusted.

  The pressure-increasing linear control valve 66 is provided as a common pressure-increasing control valve for each of the wheel cylinders 23 provided corresponding to each wheel. Similarly, the pressure reducing linear control valve 67 is provided as a pressure reducing control valve common to the wheel cylinders 23. In other words, in the present embodiment, the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are a pair of common control valves for controlling supply and discharge of the brake fluid sent from the power hydraulic pressure source 30 to each wheel cylinder 23. It is provided as.

  Here, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 corresponds to the differential pressure between the pressure of the brake fluid in the accumulator 35 and the pressure of the brake fluid in the main flow path 45, and the inlet / outlet of the pressure-reducing linear control valve 67. The pressure difference therebetween corresponds to the pressure difference between the brake fluid pressure in the main flow path 45 and the brake fluid pressure in the reservoir 34. Further, the electromagnetic driving force according to the power supplied to the linear solenoid of the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67 is F1, the spring biasing force is F2, and the pressure increasing linear control valve 66 and the pressure reducing linear control valve are Assuming that the differential pressure acting force according to the differential pressure between the inlet / outlet of 67 is F3, the relationship of F1 + F3 = F2 is established. Therefore, the differential pressure between the inlet and outlet of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67 is controlled by continuously controlling the power supplied to the linear solenoids of the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. can do.

  The power hydraulic pressure source 30 can send the brake fluid pressurized by the supply of power independently from the operation of the brake pedal 24, and includes a third hydraulic pressure circuit including the following elements. The front and rear wheel cylinders 23 communicate with each other. The third hydraulic circuit includes an accumulator pipe 39, an accumulator flow path 63, a main flow path 45, individual flow paths 41 to 44, etc. so that the hydraulic pressure of the brake fluid in the power hydraulic pressure source 30 can be transmitted to each wheel cylinder 23. It is configured to include. The accumulator pipe 39, the accumulator flow path 63, the main flow path 45, and the individual flow paths 41 to 44 form a pressure increasing flow path in the third hydraulic circuit.

  The hydraulic actuator 40 is formed with the above-described flow paths, and includes ABS holding valves 51 to 54, ABS pressure reducing valves 56 to 59, a separation valve 60, a master cut valve 64, a regulator cut valve 65, a pressure increase. Each element includes a linear control valve 66, a pressure-reducing linear control valve 67, a simulator cut valve 68, a regulator pressure sensor 71, an accumulator pressure sensor 72, a control pressure sensor 73, and the like. Then, the hydraulic actuator 40 switches the flow path of the brake fluid supplied from at least one of the master cylinder unit 10 and the power hydraulic pressure source 30 based on a control signal from the brake ECU 70, and transmits it to each wheel cylinder 23. Control the fluid pressure of the brake fluid.

  Further, since the hydraulic pressure actuator 40 is connected to the second flow path 45b of the main flow path 45 between the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67, the rear wheel regardless of whether the separation valve 60 is opened or closed. The hydraulic pressure of the side wheel cylinders 23RR and 23RL can be controlled. If the separation valve 60 is in the open state, the hydraulic pressure of all the wheel cylinders 23 can be controlled by the hydraulic actuator 40 using the hydraulic pressure of the brake fluid in the power hydraulic pressure source 30.

  In the brake control device 20, the power hydraulic pressure source 30 and the hydraulic actuator 40 are controlled by the brake ECU 70. The brake ECU 70 is configured as a microprocessor including a CPU, and includes a ROM that stores various programs, a RAM that temporarily stores data, an input / output port, a communication port, and the like in addition to the CPU. The brake ECU 70 can communicate with a host hybrid ECU (not shown) and the like, and based on control signals from the hybrid ECU and signals from various sensors, the pump 36 of the power hydraulic pressure source 30 and the hydraulic pressure Brake regeneration cooperative control can be executed by controlling the electromagnetic control valves 51 to 54, 56 to 59, 60, and 64 to 68 constituting the actuator 40.

  Further, a regulator pressure sensor 71, an accumulator pressure sensor 72, and a control pressure sensor 73 are connected to the brake ECU 70. The regulator pressure sensor 71 detects the pressure of the brake fluid in the regulator flow path 62 on the upstream side of the regulator cut valve 65, that is, the regulator pressure, and gives a signal indicating the detected value to the brake ECU 70. The accumulator pressure sensor 72 detects the pressure of the brake fluid in the accumulator flow path 63, that is, the accumulator pressure on the upstream side of the pressure increasing linear control valve 66, and gives a signal indicating the detected value to the brake ECU 70. The control pressure sensor 73 detects the pressure of the brake fluid in the first flow path 45a on one side of the separation valve 60 in the main flow path 45, and gives a signal indicating the detected value to the brake ECU 70. The detected values of the regulator pressure sensor 71, the accumulator pressure sensor 72, and the control pressure sensor 73 are sequentially given to the brake ECU 70 every predetermined time, and are stored and held in a predetermined storage area of the brake ECU 70 by a predetermined amount. In this embodiment, each of the regulator pressure sensor 71, the accumulator pressure sensor 72, and the control pressure sensor 73 has a self-diagnosis function, detects the presence or absence of abnormality in the sensor for each sensor, and the brake ECU 70 A signal indicating the presence or absence of abnormality can be transmitted.

  When the separation valve 60 is opened and the first flow path 45 a and the second flow path 45 b of the main flow path 45 communicate with each other, the output value of the control pressure sensor 73 is the low pressure of the pressure-increasing linear control valve 66. The hydraulic pressure on the high pressure side of the pressure-reducing linear control valve 67 and the output pressure value can be used for controlling the pressure-increasing linear control valve 66 and the pressure-reducing linear control valve 67. When the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are closed and the master cut valve 64 is opened, the output value of the control pressure sensor 73 indicates the master cylinder pressure. Further, the separation valve 60 is opened so that the first flow path 45a and the second flow path 45b of the main flow path 45 communicate with each other, and the ABS holding valves 51 to 54 are opened, while the ABS pressure reducing valves 56 are opened. When? 59 is closed, the output value of 73 of the control pressure sensor indicates the brake fluid pressure acting on each wheel cylinder 23, that is, the wheel cylinder pressure.

  Further, the sensor connected to the brake ECU 70 includes a stroke sensor 25 provided on the brake pedal 24. The stroke sensor 25 detects a pedal stroke as an operation amount of the brake pedal 24 and gives a signal indicating the detected value to the brake ECU 70. The output value of the stroke sensor 25 is also sequentially given to the brake ECU 70 every predetermined time, and is stored and held in a predetermined storage area of the brake ECU 70 by a predetermined amount. A brake operation state detection unit other than the stroke sensor 25 may be provided in addition to the stroke sensor 25 or in place of the stroke sensor 25 and connected to the brake ECU 70. Examples of the brake operation state detection means include a pedal depression force sensor that detects an operation force of the brake pedal 24 and a brake switch that detects that the brake pedal 24 is depressed.

  The brake control device 20 configured as described above can take at least two brake control modes of a regeneration cooperative control mode and a backup hydro booster mode (hereinafter also referred to as “HB mode”). . During normal travel, the brake control device 20 controls the braking force in the regenerative cooperative control mode. If any abnormality is detected in the brake control device 20, for example, an abnormality related to brake fluid pressure (hereinafter also referred to as “hydraulic pressure”), specifically, an abnormality in which the brake fluid pressure cannot be controlled is detected. The brake control device 20 controls the braking force in the booster mode.

  The hydro booster mode is a control mode in which a brake fluid flow path from the master cylinder 32 to the wheel cylinder 23 is secured so that a braking force is mechanically generated in response to an operation input to the brake operation member. In principle, in the hydro booster mode, the brake ECU 70 stops supplying control current to all electromagnetic control valves. Therefore, the normally open master cut valve 64 and the regulator cut valve 65 are opened, and the normally closed separation valve 60 and the simulator cut valve 68 are closed. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are stopped and closed.

  As a result, the brake fluid supply path is separated into two systems, a first hydraulic circuit and a second hydraulic circuit. The master cylinder pressure is transmitted to the front wheel wheel cylinders 23FR and 23FL, and the regulator pressure is transmitted to the rear wheel wheel cylinders 23RR and 23RL. The delivery destination of the brake fluid from the master cylinder 32 is switched from the stroke simulator 69 to the wheel cylinders 23FR and 23FL for the front wheels. Further, since the hydraulic booster 31 is a mechanism that mechanically amplifies the pedal depression force, the hydraulic booster 31 continues to function even when the control current to each electromagnetic control valve is stopped by shifting to the hydro booster mode. The hydro booster mode is excellent in fail-safe property in that a braking force can be generated using a hydraulic booster.

  In any case, the brake control device 20 starts braking in response to a braking request. The braking request is generated when a braking force should be applied to the vehicle. The braking request is, for example, when the driver operates the brake pedal 24, or when the distance from the other vehicle is narrower than a predetermined distance when the distance from the other vehicle is automatically controlled during traveling. It is born.

  FIG. 2 is a flowchart for explaining a control process in the regeneration cooperative control mode. In the regeneration cooperative control mode, brake regeneration cooperative control is executed. The processing shown in FIG. 2 is repeatedly executed at a predetermined cycle, for example, about several milliseconds after the brake pedal 24 is operated and a braking request is generated.

  When the control process in the regenerative cooperative control mode is started, the brake ECU 70 first determines whether or not the monitoring item is abnormal as needed (S12). The monitoring items as needed include, for example, the presence or absence of a disconnection or short circuit in the brake control device 20, the presence or absence of an abnormality in the power hydraulic pressure source 30 based on the measurement value of the accumulator pressure sensor 72, and the like. The monitoring item at any time is set to detect an abnormality in which the brake fluid pressure cannot be controlled in order to determine whether or not to execute or continue the regenerative cooperative control mode.

  When it is determined that there is an abnormality in the monitoring item at any time (Y in S12), the brake ECU 70 shifts the control mode from the regenerative cooperative control mode to the hydro booster (HB) mode and stops the brake regenerative cooperative control. (S24). On the other hand, when it is determined that there is no abnormality in the monitoring items as needed (N in S12), the brake ECU 70 acquires the measured values by the stroke sensor 25 and the regulator pressure sensor 71 (S14). The operation amount of the brake pedal 24 is detected by the stroke sensor 25, and the hydraulic pressure in the master cylinder unit 10 pressurized as the brake pedal 24 is depressed is measured by the regulator pressure sensor 71.

  Next, the brake ECU 70 determines whether or not there is an abnormality in the stroke sensor 25 and the regulator pressure sensor 71 based on the measured values of the stroke sensor 25 and the regulator pressure sensor 71 (S16). Abnormality of the stroke sensor 25 and / or the regulator pressure sensor 71 hinders calculation of the target hydraulic pressure. Therefore, in S16, a sensor abnormality related to the calculation of the brake fluid pressure is determined. In the present embodiment, two systems of stroke sensors 25 are provided in parallel, and the brake ECU 70 compares the measured values of the two stroke sensors 25 with the measured values of the regulator pressure sensor 71 to determine abnormal measured values. It is determined whether there is a sensor indicating. When there is a sensor indicating an abnormal measurement value different from the other two sensors, the brake ECU 70 determines that an abnormality has occurred in the sensor indicating the abnormal measurement value. If it is determined that any one of the sensors is abnormal (Y in S16), the brake ECU 70 shifts the control mode from the regenerative cooperative control mode to the HB mode and stops the brake regenerative cooperative control (S24). ).

  When it is determined that there is no abnormality in the stroke sensor 25 and the regulator pressure sensor 71 (N in S16), the brake ECU 70 calculates the target hydraulic pressure of the wheel cylinder 23 (S18). At this time, first, the brake ECU 70 calculates a required hydraulic braking force that is a braking force to be generated by the brake control device 20 by subtracting the braking force due to regeneration from the required total braking force. Here, the braking force by regeneration is supplied to the brake control device 20 from the hybrid ECU. Then, the brake ECU 70 calculates the target hydraulic pressure of the wheel cylinder 23 based on the calculated required hydraulic braking force.

  During traveling of the vehicle, the brake ECU 70 closes the master cut valve 64 and the regulator cut valve 65, opens the separation valve 60 and the simulator cut valve 68, and sets the pressure increasing linear control valve 66 and the pressure reducing linear control valve 67. Control is performed according to the target hydraulic pressure (S20). As a result, the wheel cylinder 23 is disconnected from the master cylinder unit 10 and can be supplied with the brake fluid from the power hydraulic pressure source 30. Further, the brake fluid sent from the master cylinder 32 by the driver's brake operation is supplied to the stroke simulator 69, and a reaction force corresponding to the depression force of the brake pedal 24 by the driver is created, and the driver's brake operation fee is generated. The ring is well maintained. Specifically, the pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are controlled by controlling the supply current to both control valves and adjusting the opening degree of both control valves.

  Thereafter, the brake ECU 70 performs a control hydraulic pressure response abnormality determination process for determining whether or not the hydraulic pressure of the wheel cylinder 23 is normally controlled (S22). In short, in the control hydraulic pressure response abnormality determination process S <b> 22, whether or not the wheel cylinder pressure is normally controlled is determined based on the measured value by the control pressure sensor 73. When the control hydraulic pressure response abnormality determination process S22 ends, the process shown in FIG. 2 ends, and is similarly executed again when the next execution timing arrives.

  In the control hydraulic pressure response abnormality determination process S22, an abnormality that cannot control the brake fluid pressure is determined. Specifically, it is determined whether or not there are three abnormalities: a response advance abnormality, a response delay abnormality, and a control failure. Here, the response advance abnormality means that the control hydraulic pressure exceeds the target hydraulic pressure due to an open failure or leakage abnormality of the pressure-increasing linear control valve 66, or the control valve opening cannot be controlled linearly. It means that it increases rapidly. The response delay abnormality means that the rise of the control hydraulic pressure is excessively delayed due to a closed failure of the pressure-increasing linear control valve 66 or an insufficient flow rate. Control failure refers to a state in which the control fluid pressure does not follow the target fluid pressure. For example, a state in which the deviation between the target fluid pressure and the control fluid pressure exceeds a reference deviation continues beyond a predetermined determination reference time. Say. Here, the open failure refers to an abnormal state in which the valve cannot be closed when it should be closed and becomes open, and the closed failure can be opened when the valve should be opened. It means an abnormal state that would be closed without any further.

  In the present embodiment, a fail safe is constructed when a failure occurs in the pipes constituting the second hydraulic circuit, for example, the individual flow paths 43 or 44. If the individual flow passages 43 or 44 are broken or cracked, brake fluid leaks, and a situation in which sufficient hydraulic pressure cannot be supplied to the wheel cylinders 23RR and 23RL on the rear wheel side occurs. Therefore, in this case, the occurrence of a response delay abnormality is determined.

FIG. 3 is a diagram illustrating the control hydraulic pressure acting on the wheel cylinder after a braking request. The vertical axis represents the differential pressure from the atmospheric pressure, and the horizontal axis represents the time from the occurrence of the braking request. FIG. 3 shows an initial control hydraulic pressure response immediately after the braking request. The initial response A ₁ when normal, the initial response A ₂ when the response delay is abnormal, and the initial response A ₃ when the response advance is abnormal. An example of each of these is shown. The target hydraulic pressure is indicated by a one-dot chain line in FIG. 3 and increases with time after the occurrence of the braking request. In FIG. 3, the target hydraulic pressure increases linearly, but this is only an example. Further, the response delay determination reference pressure α and the response advance determination reference pressure β are indicated by dotted lines, and the response advance determination reference time T ₀ , the response delay determination reference time T ₁ and the control failure determination time T ₂ are respectively indicated by two-dot chain lines. It is shown.

The normal initial response A ₁ has reached the response delay determination reference pressure α before the response delay determination reference time T ₁ elapses, specifically when the time t ₁ has elapsed from the braking request. The normal initial response A ₁ is continued to increase the time t ₁ later, the response delay determination reference time T ₁ exceeds the response delay determination reference pressure alpha. Thus, when the control hydraulic pressure before the elapse of the response delay determination reference time T ₁ is reached the response delay determination reference pressure α it is not determined that there is a response delay abnormality.

Here, the control hydraulic pressure is measured by the control pressure sensor 73. The response delay determination reference pressure α is set in advance as a threshold for determining the rise of the control hydraulic pressure and stored in the brake ECU 70. In this embodiment, the response delay determination reference pressure α is set to about 0.5 to 1.0 MPa, for example. The response delay determination reference time T ₁ is set in advance as a threshold value for determining a response delay abnormality in the control hydraulic pressure is stored in the brake ECU 70. Response delay determination reference time T ₁ is counted based on the time of occurrence of the braking request is set to expire before the expiry of the control failure determination time T ₂ of the later. Response delay determination reference time T ₁ and the response delay determination reference pressure alpha, it is desirable to suitably determined by experiments or the like.

Furthermore, the normal initial response A ₁ is lower than the reference deviation difference between the target fluid pressure when the elapsed time t _3, then continue to follow the target hydraulic pressure. That is, the deviation from the normal target value of the initial response A ₁ when a control failure determination time T ₂ has elapsed is smaller than the reference deviation. Thus, when the deviation between the target hydraulic pressure before a control failure determination time T ₂ has elapsed is below the reference deviation is not determined to be a control failure occurs.

Here, the reference deviation may be set to a constant value, or may be set to a predetermined ratio of the target hydraulic pressure. In this embodiment, the reference deviation is set to a constant value, for example, 1 MPa. Control failure determination time T ₂ are, is preset as a threshold value for determining the control failure of the control hydraulic pressure is stored in the brake ECU 70.

On the other hand, initial response A ₂ in the case of the response delay abnormality has reached the response delay determination reference pressure α when the time from the braking request t ₂ has elapsed. Time t ₂ is after the elapse of the response delay determination reference time T _1, the initial response A ₂ is the response delay determination reference time T ₁ not reached the response delay determination reference pressure alpha. In such a case, it is determined that a response delay abnormality has occurred.

The initial response A ₃ when the response advance abnormality, when the elapsed time t ₀ from the braking request already response advance exceeds the target hydraulic pressure reaches the determination reference pressure beta, as the control fluid pressure continues to increase, The response advance determination reference pressure β is also exceeded at the response advance determination reference time T ₀ . In this way, when the control fluid pressure suddenly increases and the control fluid pressure exceeds the response advance determination reference pressure β at the response advance determination reference time T ₀ , it is determined that a response advance abnormality has occurred. Is done.

Here, the response advance determination reference pressure β is preferably set to a value larger than the target hydraulic pressure at the response advance determination reference time T ₀ , and is set to about 3 to 4 MPa, for example. Since it is rare that the control hydraulic pressure exceeds the target hydraulic pressure immediately after the control request, if the control hydraulic pressure exceeds the target hydraulic pressure at the response advance determination reference time T ₀ immediately after the control request, the response advance is abnormal. This is because it may be determined. Response advance determination reference time T ₀ is set before the response delay determination reference time T _1. Then, since the response advance abnormality of the control hydraulic pressure is detected before the response delay abnormality, it is possible to more quickly suppress the occurrence of an excessive braking force exceeding the required braking force.

FIG. 4 is a flowchart for explaining the control hydraulic pressure response abnormality determination process S22. When the control hydraulic pressure response abnormality determination process S22 is started, the brake ECU 70 first determines whether a response advance abnormality has occurred (S40). That is, the brake ECU 70 determines whether or not the control hydraulic pressure exceeds the response advance determination reference pressure β before the response advance determination reference time T ₀ elapses from the generation of the braking request. If it is determined that the control hydraulic pressure has not reached the response advance determination reference pressure β, the brake ECU 70 determines that no response advance abnormality has occurred (N in S40), and proceeds to determination of a response delay abnormality (S40). S42). If it is determined that the control hydraulic pressure exceeds the response advance determination reference pressure β, the brake ECU 70 determines that a response advance abnormality has occurred (Y in S40). When the response advance abnormality has occurred, the brake ECU 70 stops the brake regeneration cooperative control, shifts to the hydro booster mode (S46), and ends the control hydraulic pressure response abnormality determination process S22.

Next, the brake ECU 70 determines whether or not a response delay abnormality has occurred (S42). That is, the brake ECU70 determines whether the control hydraulic pressure until the lapse of the response delay determination reference time T ₁ from generation of the braking request reaches the response delay determination reference pressure alpha. When the control hydraulic pressure before the response delay determination reference time T ₁ is passed is determined to reach the response delay determination reference pressure α, the brake ECU70 determines that the response delay abnormality has not occurred (S42 of N), it moves to the determination of control failure (S44). When the control fluid pressure even after the response delay determination reference time T ₁ is is determined not reached the response delay determination reference pressure α, the brake ECU70 determines that the response delay abnormality has occurred ( Y of S42). When the response delay abnormality has occurred, the brake ECU 70 stops the brake regeneration cooperative control, shifts to the hydro booster mode (S46), and ends the control hydraulic pressure response abnormality determination process S22.

Further, the brake ECU 70 determines whether or not a control failure has occurred (S44). That is, the brake ECU70 determines by control failure determination time T ₂ has elapsed, whether the target fluid pressure and the control hydraulic deviation calculated from the pressure falls below the reference deviation. When a control failure determination time T ₂ is determined to lower than the reference deviation until after the brake ECU70 is poor control is determined not to have occurred (S44 of N), the program returns to the processing shown in FIG. 2 . If even after the control failure determination time T ₂ is determined to deviation of the control hydraulic pressure exceeds the reference deviation, brake ECU70 determines that the control failure has occurred (S44: Y) . If a control failure has occurred, the brake ECU 70 stops the brake regeneration cooperative control, shifts to the hydro booster mode (S46), and ends the control hydraulic pressure response abnormality determination process S22.

  FIG. 5 shows a configuration of the brake ECU 70 that determines the brake control mode. The brake ECU 70 includes an abnormality detection unit 100 and a brake mode control unit 102 in order to determine a brake control mode. The abnormality detection unit 100 detects an abnormality related to the brake fluid pressure. Here, the abnormality relating to the brake fluid pressure is, as described with reference to FIG. 2, a failure in a sensor or wiring necessary for executing the brake regeneration cooperative control, or as described with reference to FIG. 4. An abnormality in which the brake fluid pressure cannot be controlled due to the occurrence of a fluid pressure response abnormality. That is, in the present embodiment, the abnormality detection unit 100 performs the determination processing of S12 and S16 in FIG. 2 and also performs the determination processing of S40, S42, and S44 in FIG. 4 to detect an abnormality related to the brake fluid pressure. .

  When the abnormality detection unit 100 detects an abnormality related to the brake fluid pressure, the brake mode control unit 102 stops the brake regeneration cooperative control and shifts the brake control mode to the hydro booster mode. The brake mode control unit 102 stops the supply of the control current to all the electromagnetic control valves, and executes the brake control in the hydro booster mode. Therefore, the normally open master cut valve 64 and the regulator cut valve 65 are opened, and the normally closed separation valve 60 and the simulator cut valve 68 are closed. The pressure-increasing linear control valve 66 and the pressure-decreasing linear control valve 67 are stopped and closed.

  In the brake regeneration cooperative control mode of this embodiment, each wheel is controlled such that the supply and discharge of the brake fluid to and from the wheel cylinder 23 of each wheel is controlled by a pair of pressure increasing linear control valve 66 and pressure reducing linear control valve 67. A pressure-increasing linear control valve 66 and a pressure-decreasing linear control valve 67 are made common to the cylinder 23. For this reason, it is preferable from a viewpoint of cost reduction compared with providing a control valve for every wheel cylinder 23. FIG. However, if the pressure-increasing linear control valve 66 and the like are made common, the volume to be supplied increases with respect to the supply flow rate, so that the delay time of the rise of the control hydraulic pressure becomes long. Therefore, in this embodiment, the response delay is determined in two stages, such as the response delay abnormality and the control failure determination as described above. By doing so, it is possible to quickly detect an abnormality in which the brake fluid pressure cannot be controlled, for example, a leakage abnormality due to a pipe failure or an excessive response delay due to an abnormality such as a closed failure of the pressure increasing linear control valve 66. it can. Therefore, it is possible to quickly shift to the hydro booster mode at the time of abnormality, and quickly eliminate the state where the braking force is insufficient.

  As described above, in the regenerative cooperative control mode, the brake fluid sent from the power hydraulic pressure source 30 is supplied to the wheel cylinder 23 via the pressure-increasing linear control valve 66, and braking force is applied to the wheels. Further, the brake fluid is discharged from the wheel cylinder 23 as necessary through the pressure-reducing linear control valve 67, and the braking force applied to the wheel is controlled.

  On the other hand, in the hydro booster mode, the hydraulic pressure in the master cylinder unit 10 pressurized according to the driver's brake operation amount is transmitted to the wheel cylinder 23. In the hydro booster mode, the brake ECU 70 opens the master cut valve 64 and the regulator cut valve 65, and closes the separation valve 60 and the simulator cut valve 68. As a result, the master cylinder pressure is transmitted to the front wheel side wheel cylinders 23FR and 23FL via the first hydraulic pressure circuit, and the regulator pressure is transferred to the rear wheel side wheel cylinders 23RR and 23RL via the second hydraulic pressure circuit. The transmitted braking force is applied to each wheel.

  In the present embodiment, as described above, the hydro booster mode is used as a preliminary control mode when the brake regeneration cooperative control is not performed due to an abnormality or the like. In the hydro booster mode, the first hydraulic circuit and the second hydraulic circuit are separated by closing the separation valve 60. This is because even if a further abnormality such as a liquid leak from the pipe occurs in any of the hydraulic circuits, the braking force can be applied by the normal hydraulic circuit. By providing the separation valve 60 in this way, the safety of the brake control device 20 can be further improved.

  Thus, the separation valve 60 serves to separate the first hydraulic circuit for the front wheels and the second hydraulic circuit for the rear wheels in the hydro booster mode. Even when a failure occurs in the piping and the brake fluid of the second hydraulic circuit leaks to the outside, the hydraulic pressure can be supplied to the wheel cylinder 23 for the front wheels via the first hydraulic circuit. In the hydro booster mode, the control pressure sensor 73 detects the brake fluid pressure Pfr of the first hydraulic circuit, and the regulator pressure sensor 71 detects the brake fluid pressure Prr of the second hydraulic circuit.

  However, in the present embodiment, the separation valve 60 is configured by a differential pressure valve that opens when the differential pressure before and after the separation valve reaches a predetermined value P1 or more. The closed state of the separation valve 60 is realized by a spring. Therefore, the difference between the hydraulic pressure Pfr of the first flow path 45a and the hydraulic pressure Prr of the second flow path 45b when the hydraulic circuit is separated into two systems. When the pressure exceeds the self-opening pressure P1 (for example, 9 MPa) due to the spring force, the valve opens, and the brake fluid leaks from the first flow path 45a on the high pressure side to the second flow path 45b on the low pressure side. Hereinafter, this phenomenon will be described.

  FIG. 6 is a diagram showing the internal configuration of the reservoir 34 and the connection configuration with the piping. The reservoir 34 is supplied with a reservoir pipe 77 for circulating the brake fluid from the wheel cylinder 23, a pump pipe 78 for supplying the brake fluid to the power hydraulic pressure source 30, and the brake fluid is supplied to the master cylinder 32 and the regulator 33, respectively. Therefore, the first pipe 81 and the second pipe 82 are connected. The tank of the reservoir 34 is partitioned by a partition wall 83 into a first reservoir chamber 84 that stores brake fluid for the master cylinder 32 and a second reservoir chamber 85 that stores brake fluid for the regulator 33.

  A decrease determination line 86 indicated by a dotted line indicates a reference for determining a decrease in the amount of brake fluid in the tank. The reservoir 34 outputs an OFF signal if the fluid level of the brake fluid is above the decrease determination line 86, and a storage amount decrease detection switch 87 that outputs an ON signal if the fluid level of the brake fluid falls below the decrease determination line 86. Prepare. The reservoir 34 is provided with means for detecting the brake fluid amount, the detected value is notified to the brake ECU 70, and the brake ECU 70 determines whether or not the brake fluid amount has decreased below the reference value specified by the decrease determination line 86. It may be determined.

  When the amount of brake fluid in the tank decreases and the liquid level further falls below the decrease determination line 86, the upper end of the partition wall 83 is reached. For example, when a fluid leak occurs in the individual flow path 43 of the second hydraulic circuit, the first reservoir chamber 84 is separated by the partition wall 83 even if the brake fluid in the second reservoir chamber 85 does not leak to the outside. Since the two reservoir chambers 85 are separated from each other, the fluid level of the brake fluid in the first reservoir chamber 84 does not fall below the upper end of the partition wall 83, and the first hydraulic circuit can be maintained in an operable state. When all the brake fluid in the second hydraulic circuit leaks, the pressure values detected by the regulator pressure sensor 71 and the accumulator pressure sensor 72 are reduced to zero.

  In this state, when the brake pedal 24 is depressed with a high depression force of, for example, 900 N or more, only the brake fluid of the first hydraulic circuit is boosted. Therefore, when the differential pressure (Pfr−Prr) in the separation valve 60 increases and exceeds the self-opening pressure P1, the separation valve 60 may open. At this time, if the hydraulic pressure in the second flow path 45 b is substantially zero, the hydraulic pressure Pfr in the first flow path 45 a is substantially equal to the differential pressure in the separation valve 60.

  When the hydraulic pressure in the first flow path 45a exceeds the self-opening pressure (9 MPa), the separation valve 60 is opened, so that the brake fluid in the first hydraulic circuit passes through the separation valve 60 and the second hydraulic circuit side. Flow into. At this time, the brake fluid amount of the first hydraulic circuit is reduced by the amount flowing into the second hydraulic circuit. The inventor has confirmed through experiments that the liquid level of the brake fluid in the first hydraulic circuit drops to the vicinity of the boundary between the first pipe 81 and the master chamber 79 after repeating this operation several tens of times. If the brake pedal 24 is returned in a state where the brake fluid is in the vicinity of the boundary between the first pipe 81 and the master chamber 79, air enters the master chamber 79 and the hydraulic pressure is unlikely to increase.

In order to solve the above problems, for example, the following measures can be considered.
As a first countermeasure, it is conceivable to increase the self-opening pressure by increasing the spring constant of the separation valve 60 to increase the spring force.
In the above example, the self-opening pressure P1 is set to 9 MPa. However, by increasing the self-opening pressure by increasing the spring force, the separation valve 60 that is difficult to open due to the differential pressure before and after in the hydro booster mode is configured. it can. However, in a normal state, that is, in the regenerative cooperative control mode, there is a problem that a large current is required to supply the current to the separation valve 60 to open the valve.

  As a second countermeasure, it is conceivable to increase the self-opening pressure by reducing the orifice of the separation valve 60 and increasing the flow path resistance. This solves the problem of current increase, which is a problem in the first countermeasure in the regenerative cooperative control mode, but the brake fluid flowing in from the pressure-increasing linear control valve 66 is slow to reach the first flow path 45a, There is a problem that the vehicle behavior becomes unstable because the pressure increase of the wheel cylinder 23 on the rear wheel side precedes.

  Therefore, the brake control device 20 of the present embodiment performs a leak suppression process for suppressing the brake fluid in the first hydraulic circuit from flowing into the second hydraulic circuit in the hydro booster mode in which the separation valve 60 is in the closed state. Run.

  FIG. 7 is a flowchart for explaining basic control of the leakage suppression process of the present embodiment. The brake ECU 70 determines whether the brake control mode is the HB mode (S100). If it is not the HB mode (N in S100), the leakage suppression process is not executed. In the HB mode (Y in S100), the brake ECU 70 determines whether or not the differential pressure between the brake fluid pressure Pfr of the first hydraulic circuit and the brake fluid pressure Prr of the second hydraulic circuit exceeds a predetermined value P2. (S102). Here, the predetermined value P2 is set to a value smaller than the self-opening pressure P1 of the separation valve 60. In the hydro booster mode, Pfr is detected by the control pressure sensor 73, and Prr is detected by the regulator pressure sensor 71. The differential pressure (Pfr−Prr) is a pressure value applied before and after the separation valve 60.

  By setting the predetermined value P2 to be smaller than the self-opening pressure P1 of the separation valve 60, if the differential pressure (Pfr−Prr) is equal to or less than P2 (N in S102), the differential pressure applied to the separation valve 60 is self-opening. Therefore, the separation valve 60 does not open. Therefore, in this state, the brake fluid in the first hydraulic circuit does not flow into the second hydraulic circuit via the separation valve 60.

  On the other hand, if the differential pressure (Pfr−Prr) exceeds P2 (Y in S102), the differential pressure may eventually reach P1 and the separation valve 60 may open. Therefore, a leakage suppression process is performed to suppress the brake fluid in the first hydraulic circuit from flowing into the second hydraulic circuit before the differential pressure between Pfr and Prr exceeds the self-opening pressure P1 (S104). Specifically, the brake ECU 70 closes a predetermined control valve to suppress an increase in the brake fluid pressure of the first hydraulic circuit so that the differential pressure between Pfr and Prr does not exceed the self-opening pressure P1. In the present embodiment, the brake ECU 70 closes the master cut valve 64 provided in the middle of the reservoir 34 and the separation valve 60 so that the hydraulic pressure supplied from the master cylinder 32 is shut off by the master cut valve 64. An increase in hydraulic pressure downstream of the master cut valve 64 is suppressed. As a result, the brake control device 20 can supply the brake fluid pressure Pfr when the master cut valve 64 is closed to the wheel cylinder 23 for the front wheels while maintaining the fluid amount of the first hydraulic circuit.

The basic control of the leakage suppression process has been described above, but will be described in more detail below.
FIG. 8 shows a configuration of the brake ECU 70 that executes the leakage suppression process. The brake ECU 70 includes a condition determination unit 110 and a leakage suppression unit 150. The leak suppression unit 150 controls execution and cancellation of the leak suppression process, and controls the opening and closing of the master cut valve 64 in the present embodiment. The condition determination unit 110 performs a condition determination process for determining a control policy in the leakage suppression unit 150. The condition determination unit 110 includes an HB mode determination unit 108, a storage amount determination unit 112, a disconnection determination unit 114, a pressure drop abnormality determination unit 116, a pipe failure determination unit 118, a differential pressure determination unit 120, a hydraulic pressure determination unit 122, It has a pressure state determination unit 124, a travel mode determination unit 126, and an abnormality determination unit 128.

  In FIG. 8, each element described as a functional block for performing various processes can be configured by a CPU (Central Processing Unit), a memory, and other LSIs in terms of hardware. This is realized by a program loaded on the computer. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof, and is not limited to any one.

  FIG. 9 is a flowchart for explaining details of the control of the leakage suppression process of the present embodiment. The HB mode determination unit 108 determines whether the brake control mode is the HB mode (S110). If it is not the HB mode (N of S110), the leakage suppression process is not executed. In the HB mode (Y in S110), the condition determination unit 110 determines whether or not a failure has occurred in the rear piping (S112). The piping failure determination process S112 is executed by the storage amount determination unit 112, the disconnection determination unit 114, the pressure drop abnormality determination unit 116, and the pipe failure determination unit 118.

  FIG. 10 is a flowchart for explaining the pipe failure determination process S112. First, the storage amount determination unit 112 receives a signal from the storage amount decrease detection switch 87 and determines whether or not the storage amount of the reservoir 34 is normal (S130). Here, the OFF signal sent from the storage amount decrease detection switch 87 indicates that the fluid level of the brake fluid is above the decrease determination line 86, and the ON signal indicates that the liquid level is below the decrease determination line 86. Indicates. Therefore, when the storage amount determination unit 112 receives the OFF signal, the storage amount determination unit 112 determines that the storage amount is normal (Y in S130), and the pipe failure determination unit 118 determines that no pipe failure has occurred. (S138).

  On the other hand, when receiving the ON signal, the storage amount determination unit 112 determines that the storage amount of the reservoir 34 is not normal (N in S130). As a result, it is determined that the brake fluid amount in the reservoir 34 is lower than the reference value specified by the decrease determination line 86. At this time, the disconnection determination unit 114 determines whether a failure has occurred in the storage amount decrease detection switch 87, specifically, whether a disconnection has occurred (S132). When disconnection has occurred (Y in S132), the ON signal from the storage amount decrease detection switch 87 is not reliable, so the pipe failure determination unit 118 determines that no pipe failure has occurred ( S138).

  When no disconnection has occurred (N in S132), the pressure drop abnormality determination unit 116 determines that the brake fluid pressure Prr of the second hydraulic circuit and / or the brake of the accumulator flow path upstream of the pressure-increasing linear control valve 66 is used. Using the fluid pressure Pacc, it is determined whether there is a pressure drop abnormality (S134). The brake fluid pressure Prr of the second hydraulic circuit is detected by the regulator pressure sensor 71, and the brake fluid pressure Pacc of the accumulator flow path is detected by the accumulator pressure sensor 72. The pressure drop abnormality determination unit 116 may execute the pressure drop abnormality determination process using two brake fluid pressures of the second hydraulic circuit and the accumulator flow path, but may use only one of them. Good. If it is not determined that the pressure drop is abnormal (N in S134), the pipe failure determination unit 118 determines that no pipe failure has occurred (S138), and determines that the pressure drop is abnormal. In the case (Y in S134), the pipe failure determination unit 118 determines that a pipe failure has occurred (S136), and detects leakage of brake fluid to the outside in the second hydraulic circuit. In this way, the pipe failure determination unit 118 also functions as a leak detection unit that detects a brake fluid leak to the outside of the hydraulic circuit. Hereinafter, the pressure drop abnormality determination process S134 performed by the pressure drop abnormality determination unit 116 will be described.

  FIG. 11 is a flowchart for explaining the pressure drop abnormality determination process S134. The pressure drop abnormality determination unit 116 compares the brake fluid pressure Prr of the second hydraulic circuit with the predetermined value P3 (S150). The predetermined value P3 is set to a value within the range of 0.5 to 1 MPa, for example. When the brake fluid pressure Prr of the second hydraulic circuit is equal to or higher than P3 (N in S150), the pressure drop abnormality determination unit 116 determines that no pressure drop abnormality has occurred (S156).

  When the brake fluid pressure Prr of the second hydraulic circuit is smaller than P3 (Y in S150), the pressure drop abnormality determination unit 116 compares the brake fluid pressure Pacc in the accumulator flow path with a predetermined value P4 (S152). . The predetermined value P4 is set to a value of about 2 MPa, for example. When the brake fluid pressure Pacc in the accumulator channel is equal to or higher than P4 (N in S152), the pressure drop abnormality determination unit 116 determines that no pressure drop abnormality has occurred (S156). On the other hand, when the brake fluid pressure Pacc in the accumulator flow path is smaller than P4 (Y in S152), the pressure drop abnormality determination unit 116 determines that a pressure drop abnormality has occurred (S154).

  As described in the flowchart of FIG. 10, the determination result of the pressure drop abnormality in S <b> 134 is used as a determination condition for the occurrence of failure in the rear piping. The pipe failure determination unit 118 determines the occurrence of pipe failure when the storage amount of the reservoir 34 is lower than the reference value and it is determined that the pressure drop is abnormal, thereby preventing leakage of brake fluid to the outside. It becomes possible to detect with high accuracy.

Since the brake fluid pressure varies with time, in order to prevent erroneous determination, the presence or absence of a pressure drop abnormality may be determined by adding a time condition.
FIG. 12 is a flowchart in which a time condition is added to the pressure drop abnormality determination process S134 shown in FIG. The pressure drop abnormality determination unit 116 acquires the brake fluid pressures Prr and Pacc from the regulator pressure sensor 71 and the accumulator pressure sensor 72 at a predetermined cycle. The determination process of the pressure drop abnormality shown in FIG. 12 is executed every time the pressure drop abnormality determination unit 116 acquires the detection value of each sensor, and the detection value of each sensor is processed in parallel.

  First, the determination process of the brake fluid pressure Prr of the second hydraulic circuit will be described. The pressure drop abnormality determination unit 116 compares the brake fluid pressure Prr with a predetermined value P3 (S170). If the brake fluid pressure Prr is smaller than P3 (Y in S170), the pressure drop abnormality determining unit 116 outputs an H value to the buffer memory (not shown) as a comparison result (S172), and the brake fluid pressure Prr is equal to or higher than P3. Or if comparison is not possible (N in S170), the L value is output to the buffer memory as a comparison result (S174). This comparison is executed in a predetermined cycle, and the buffer memory holds a comparison result for a predetermined time (> time Ta).

  The pressure drop abnormality determination unit 116 refers to the comparison results held in the buffer memory from the latest comparison result to the time Ta before, and determines whether the H value is continuously output at that time (time Ta) ( S176). If all the comparison results are H values, the pressure drop abnormality determination unit 116 determines that the state in which the brake fluid pressure Prr is lower than the predetermined value P3 continues for a time Ta (Y in S176), and uses the H value as a determination value. Is output to a determination memory (not shown) (S178). On the other hand, if even one L value exists in the comparison result, the pressure drop abnormality determination unit 116 determines that the state where the brake fluid pressure Prr is lower than the predetermined value P3 does not continue for the time Ta (N in S176). ), The L value is output as a determination value to the determination memory (S180). The determination process in S176 is executed each time the comparison process in S170 is performed, and the value in the determination memory is updated each time.

  Similarly, the pressure drop abnormality determination unit 116 compares the accumulator pressure Pacc and the predetermined value P4 (S190). If the accumulator pressure Pacc is smaller than P4 (Y in S190), the pressure drop abnormality determination unit 116 outputs the H value as a comparison result to the buffer memory (S192), and if the accumulator pressure Pacc is P4 or more, or if the comparison is If not possible (N in S190), the L value is output to the buffer memory as a comparison result (S194). This comparison is executed at a predetermined cycle, and the buffer memory holds a comparison result for a predetermined time (> time Tb).

  The pressure drop abnormality determination unit 116 refers to the comparison results held in the buffer memory from the latest comparison result to the time Tb before, and determines whether or not the H value is continuously output for the time Tb at that time ( S196). If all the comparison results are H values, the pressure drop abnormality determination unit 116 determines that the state where the accumulator pressure Pacc is lower than the predetermined value P4 continues for a time Tb (Y in S196), and uses the H value as the determination value. The data is output to the determination memory (S198). On the other hand, if at least one L value exists in the comparison result, the pressure drop abnormality determination unit 116 determines that the state where the accumulator pressure Pacc is lower than the predetermined value P4 does not continue for the time Tb (N in S196). The L value is output to the determination memory as the determination value (S200). The determination process in S196 is executed each time the comparison process in S190 is performed, and the value in the determination memory is updated each time.

  The pressure drop abnormality determination unit 116 refers to the two determination values output to the determination memory and determines whether both are H values (S202). If both are H values (Y in S202), both Prr and Pacc are abnormal values, and the pressure drop abnormality determining unit 116 determines that a pressure drop abnormality has occurred (S204). Thus, by determining the pressure drop state using the duration condition, it is possible to accurately determine the pressure drop abnormality. If at least one of the two determination values is an L value (N in S202), the pressure drop abnormality determination unit 116 determines that no pressure drop abnormality has occurred (S206).

  Incidentally, the brake ECU 70 has a function of executing a system check at the time of activation. In the system check, the operation of the solenoid valve is inspected to check whether normal brake control can be executed. This system check is executed when the vehicle door is opened or when the brake pedal 24 is depressed in the ignition-off state.

  FIG. 13 shows processing and state value transition when a pipe failure occurs when the ECU is activated. The horizontal axis represents the time axis. FIG. 13A shows a state value of the brake determination, OFF indicates a state where the brake pedal 24 is not depressed, and ON indicates a state where the brake pedal 24 is depressed. FIG. 13B shows the activation state value of the brake ECU 70, OFF indicates a state where the brake ECU 70 is not activated, and ON indicates a state where the brake ECU 70 is activated. In the example shown in FIG. 13B, the brake ECU 70 is activated when the brake pedal 24 is depressed.

  FIG. 13C shows the transition of the brake control mode. In this example, it is assumed that the hydro booster mode is executed directly from the system check. A system check is executed immediately after the brake ECU 70 is started, and the hydro booster mode is executed after the elapse of time Ts.

  FIG. 13D shows a comparison value between the accumulator pressure Pacc and the predetermined value P4. Here, the L value indicates a state that is not (Pacc <P4) or a state that cannot be compared, and the H value indicates a state that is determined to be (Pacc <P4). In this example, since the comparison between Pacc and P4 cannot be performed during the system check, the L value is output. On the other hand, after the system check is completed, it is determined that (Pacc <P4) and the H value is output. Has been. This is, for example, as described in S190 of FIG.

  In addition, as described with reference to S196 in FIG. 12, when the H value indicating that (Pacc <P4) is continuously output for the time Tb, the pressure drop abnormality determination unit 116 indicates that the accumulator pressure Pacc has a pressure drop abnormality. Determine that it has occurred. As will be described later with reference to FIG. 9 and other drawings, the leak suppression process is executed if other conditions for executing the leak suppression process are satisfied together with the abnormal pressure drop condition shown in FIG. FIG. 13 (e) is based on the premise that when the H value indicating (Pacc <P4) is continuously output for the time Tb after the system check is completed, other conditions are also satisfied. The state in which the leakage suppression process is executed is shown.

  When the brake ECU 70 is activated, the execution condition of the leakage suppression process is determined after the system check is completed. Assuming that the system check takes time Ts, the leakage suppression process starts at the earliest after a time (Ts + Tb) from the activation of the brake ECU 70. As described above, when the brake ECU 70 is activated by stepping on the brake pedal 24, the brake pedal 24 has already been stepped on, so it is preferable that the determination of the pressure drop abnormality be completed earlier than usual. .

  Therefore, immediately after the end of the system check, the pressure drop abnormality determining unit 116 determines a pressure drop abnormality of the accumulator pressure Pacc when the state where the accumulator pressure Pacc is lower than the predetermined value P4 continues for a time Tc shorter than the time Tb. FIG. 13F shows a state in which the leakage suppression process is executed after time Tc on the assumption that other execution conditions are satisfied after the system check is completed. Thus, especially after the system check, it is preferable to set the time condition in the pressure drop abnormality determination to be short so that the leakage suppression process can be executed earlier than usual. In this early determination process, referring to FIG. 12, it is determined whether or not the system check is being performed before the time Tc before S196. If the system check is being performed before the time Tc, H continues for the time Tc. If this is not the case, it is executed by outputting the L value to the determination memory. If the system check is not in progress before time Tc, S196 already described is executed.

  Although FIG. 13 shows an example of shortening the time condition Tb of the accumulator pressure Pacc, referring to S176 and S196 of FIG. 12, the time condition Ta of the brake fluid pressure Prr of the second hydraulic circuit is shortened. Alternatively, the longer one of the time conditions Ta and Tb may be shortened.

  Returning to FIG. As described above with reference to FIGS. 10 to 13, the pipe failure determination unit 118 does not determine that a failure has occurred in the rear pipe based on the pressure drop abnormality determination result or the like (N in S112). When the leakage suppression process is not executed and it is determined that a failure has occurred (Y in S112), the brake ECU 70 executes a differential pressure determination process S114.

  The differential pressure determination process S114 corresponds to the process shown as S102 in FIG. The differential pressure determination unit 120 determines whether the differential pressure between the brake fluid pressure Pfr of the first hydraulic circuit and the brake fluid pressure Prr of the second hydraulic circuit exceeds a predetermined value P2 (S114). The predetermined value P2 is preferably set to be slightly smaller than the self-opening pressure P1 of the separation valve 60, and it is preferable to refrain from performing the leakage suppression process until immediately before the separation valve 60 self-opens due to the differential pressure. If the differential pressure does not exceed the predetermined value P2 (N in S114), the leakage suppression process is not executed, and if the differential pressure exceeds the predetermined value P2 (Y in S114), the brake ECU 70 determines the brake fluid pressure Pfr. This determination process S116 is executed.

  The hydraulic pressure determination unit 122 determines whether or not the brake fluid pressure Pfr of the first hydraulic pressure circuit exceeds a predetermined value P5 (S116). The hydraulic pressure determination unit 122 determines whether or not Pfr has reached a pressure sufficient to execute the leakage suppression process by comparing Pfr and P5. In the leakage suppression process of the present embodiment, as already described with respect to S104 in FIG. 7, the brake ECU 70 closes the master cut valve 64 so that the hydraulic pressure supplied from the master cylinder 32 is blocked by the master cut valve 64. Then, an increase in hydraulic pressure downstream of the master cut valve 64 is suppressed. After the master cut valve 64 is closed, the brake fluid of the first hydraulic circuit is not boosted. Therefore, when the leakage suppression process is executed, that is, when the master cut valve 64 is closed, Pfr ensures sufficient braking force. The necessary pressure needs to be reached. Therefore, the predetermined value P5 is set to a pressure that ensures a sufficient braking force, for example, a value that satisfies the legal performance. When Pfr is equal to or less than P5 (N in S116), the leakage suppression process is not executed. When Pfr exceeds P5 (Y in S116), the leakage suppression process can be executed.

  When the brake fluid pressure Pfr is greater than the predetermined value P5, the pressurization state determination unit 124 determines the pressurization state of the first hydraulic circuit (S118). Here, the pressurization state determination unit 124 can determine whether or not the first hydraulic circuit is in a state of being pressurized, and if it is in a state of further pressurization, the degree of pressurization. For example, the pressurization state determination unit 124 determines the pressurization state of the first hydraulic circuit from the output of the stroke sensor 25. The stroke sensor 25 detects a pedal stroke as an operation amount of the brake pedal 24, and the pressurization state determination unit 124 acquires the detected stroke amount ST. Note that the pressurization state determination unit 124 may determine the pressurization state of the first hydraulic circuit from the presence or absence of the accelerator operation.

  In the present embodiment, when the brake pedal 24 is depressed with a high depression force, the separation valve 60 is opened to suppress the flow of brake fluid from the first hydraulic circuit to the second hydraulic circuit. However, when detecting that the stroke amount ST exceeds the predetermined amount L1 [mm] (Y in S118), the pressurization state determination unit 124 determines that the brake pedal 24 has been depressed with a high depression force. By determining the pressurization state in this way, it can be estimated that the brake pedal 24 is depressed with a high depression force, and the leakage suppression process can be executed. If the stroke amount ST is equal to or less than L1 (N in S118), the pressurization state determination unit 124 determines that the brake pedal 24 is not depressed with a high depression force, and the leakage suppression process is not executed. The predetermined value L1 needs to be set to a large value (for example, 30 mm) in order to determine that the pedal is depressed with a high pedaling force, but is simply in a state where the first hydraulic circuit is pressurized. If it is the objective to determine this, you may set to a small value (for example, 5 mm). When two stroke sensors 25 are provided, the stroke amount ST may be derived from the average of the two detection values.

  When the first hydraulic pressure circuit is in a pressurized state, the traveling mode determination unit 126 determines whether the vehicle is in the traveling mode (S120). Specifically, the traveling mode determination unit 126 determines whether the vehicle is in the inspection mode or the maintenance mode, and determines that the vehicle is in the traveling mode if the vehicle is not in the inspection mode or the maintenance mode (S120). Y). On the other hand, if the vehicle is not in the travel mode (N in S120), the leakage suppression process is not executed.

  FIG. 14 is a flowchart for explaining the travel mode determination process S120. The brake control device 20 acquires and sets mode information from the outside according to the environment in which the vehicle is placed. After shipment, as the mode information, a travel mode flag indicating that the vehicle is ready to travel is set by default. During the inspection in the factory, an inspection mode flag indicating that the inspection is being performed is supplied from the inspection device. During vehicle maintenance at the dealer, a maintenance mode flag indicating that maintenance is in progress is supplied from the maintenance equipment. It should be noted that an air bleeding mode flag may be supplied when air bleeding is performed especially during maintenance.

  The traveling mode determination unit 126 determines whether the vehicle is being maintained based on whether the maintenance mode flag is set (S220). If the maintenance mode flag is set (Y in S220), it is determined that the vehicle is not in the traveling mode (S228). When the maintenance mode flag is not set (N in S220), the traveling mode determination unit 126 determines whether the vehicle is bleeding, depending on whether the bleeding mode flag is set (S222). If the air bleeding mode flag is set (Y in S222), it is determined that the vehicle is not in the traveling mode (S228). When the air bleeding mode flag is not set (N in S222), the traveling mode determination unit 126 determines whether the vehicle is being inspected based on whether or not the inspection mode flag is set (S224). If the inspection mode flag is set (Y in S224), it is determined that the vehicle is not in the travel mode (S228). When the inspection mode flag is not set (N in S224), the traveling mode determination unit 126 determines that the vehicle is in the traveling mode (S226). The travel mode determination unit 126 may determine whether or not the vehicle is in the travel mode by referring only to the travel mode flag.

  Returning to FIG. If it is determined in S120 that the vehicle is not in the travel mode (N in S120), the leakage suppression process is not executed. On the other hand, if it is determined that the vehicle is in the travel mode (Y in S120), since all execution conditions are satisfied, the leakage suppression unit 150 causes the brake fluid in the first hydraulic circuit to be in the second hydraulic circuit. A leakage suppression process for suppressing inflow is executed (S122).

  The leakage suppression process S122 corresponds to the process shown as S104 in FIG. The leak suppression unit 150 closes the master cut valve 64 so that the hydraulic pressure supplied from the master cylinder 32 is blocked by the master cut valve 64 and suppresses an increase in the hydraulic pressure downstream of the master cut valve 64. As a result, the brake control device 20 can supply the brake fluid pressure Pfr when the master cut valve 64 is closed to the wheel cylinder 23 for the front wheels while maintaining the fluid amount of the first hydraulic circuit. In addition, the leak suppression part 150 may suppress the leak of brake fluid by reducing the differential pressure | voltage of the separation valve 60 besides closing the master cut valve 64. FIG. For example, by opening the ABS pressure reducing valves 56 and 57 for a short time, the brake fluid may be released to the reservoir piping 77 to avoid an increase in the hydraulic pressure of the first hydraulic pressure circuit, and the differential pressure of the separation valve 60 may be reduced. . In this case, the valve opening amounts of the ABS pressure reducing valves 56 and 57 are adjusted so that a sufficient brake fluid pressure can be supplied to the wheel cylinder 23 for the front wheels.

  The above describes the control for determining the conditions for executing the leakage suppression process and executing the leakage suppression process when the conditions are satisfied. In the following, a description will be given of control for temporarily stopping or canceling the leakage suppression process depending on the situation during the execution of the leakage suppression process.

  FIG. 15 shows the transition of state values and state quantities when the leakage suppression process is executed after the brake fluid pressure Pfr of the first hydraulic pressure circuit exceeds P5 and the other conditions are satisfied in S116 of FIG. Indicates. FIG. 15A shows the stroke amount detected by the stroke sensor 25. FIG. 15C shows the transition of Pfr. As described with reference to FIG. 9, when Pfr exceeds P5, the leakage suppression process is executed by satisfying other conditions. FIG. 15B shows a state in which the leakage suppression process is executed on the premise that other conditions are also satisfied when Pfr exceeds P5.

  When the leak suppression process is executed, the master cut valve 64 is closed, so that Pfr is sealed. Normally, Pfr maintains the hydraulic pressure of P5 as indicated by a one-dot chain line as Pfr_1. However, since the fluid viscosity is high at low temperatures, the brake fluid is clogged for a short time at the orifices of the ABS holding valves 51 and 52 of the first hydraulic circuit. Therefore, at the time of low temperature, after the master cut valve 64 is closed, the brake fluid is delayed and flows into the individual flow paths 41 and 42. Therefore, as shown by a solid line as Pfr_2, a situation where Pfr cannot maintain P5 may occur. Under such circumstances, if the master cut valve 64 is maintained in the closed state, the brake fluid of the first hydraulic circuit is not increased, and it may be impossible to supply sufficient hydraulic pressure to the wheel cylinder 23.

  FIG. 16 is a flowchart for explaining a temporary stop process of the leakage suppression process. If the leakage suppression process is not being executed (N in S240), the temporary stop process is not executed. During the execution of the leakage suppression process (Y in S240), the hydraulic pressure determination unit 122 monitors the detection result by the control pressure sensor 73 (S242). If the brake fluid pressure Pfr is greater than or equal to the predetermined value P6 (N in S242), the brake fluid pressure Pfr is maintained at a normal value, and the hydraulic pressure determination unit 122 continues to monitor.

  When the brake fluid pressure Pfr drops below the predetermined value P6 (Y in S242), the hydraulic pressure determination unit 122 sends a leakage suppression process stop command to the leakage suppression unit 150. The predetermined value P6 is smaller than the predetermined value P5, but is set to a pressure that ensures a sufficient braking force, for example, a value that satisfies the regulatory performance. In order to avoid erroneous determination, the hydraulic pressure determination unit 122 may send a leakage suppression process stop command because the state in which Pfr is lower than P6 continues for a predetermined time. When receiving the stop command, the leak suppression unit 150 temporarily stops the leak suppression process (S244), specifically stops the current supply to the master cut valve 64 and opens the master cut valve 64. As a result, the first hydraulic pressure circuit is boosted by receiving the hydraulic pressure from the master cylinder 32, and when Pfr exceeds P5, the leakage suppression unit is assumed on the assumption that the other conditions described with reference to FIG. 9 are also satisfied. 150 re-executes the leak suppression process.

  FIG. 17 shows the transition of state values and state quantities when the brake fluid pressure Pfr of the first hydraulic circuit is maintained between P6 and P5. FIG. 17A shows the stroke amount detected by the stroke sensor 25 as in FIG. 15A. FIG. 17B shows the state transition of execution and stop of the leakage suppression process, and FIG. 17C shows the transition of Pfr.

  When Pfr exceeds P5, the leak suppression unit 150 executes the leak suppression process. On the other hand, when Pfr is lower than P6, the leak suppression unit 150 temporarily stops the leak suppression process. By this control, the brake fluid pressure Pfr of the first hydraulic circuit is held between P6 and P5. By setting P6 to a pressure value for ensuring a sufficient braking force, the brake control device 20 can create a sufficient braking force even during the leakage suppression process.

  FIG. 18 is a flowchart for explaining an example of the cancellation process of the leakage suppression process. If the leakage suppression process is not being executed (N in S260), the cancel process is not executed. During execution of the leakage suppression process (Y in S260), the pressurization state determination unit 124 determines the presence or absence of a braking request from the pedal stroke amount detected by the stroke sensor 25 (S262). When the pedal stroke amount is not 0, the pressurization state determination unit 124 determines that there is a braking request (N in S262), and then determines whether or not an accelerator operation is performed (S264). If the depression of the access pedal is not detected, the pressurization state determination unit 124 determines that there is no accelerator operation (N in S264).

  A state where there is a braking request (N in S262) and there is no accelerator operation (N in S264) is considered to be a situation where the first hydraulic circuit is pressurized. Therefore, in this case, the leakage suppression process is continuously executed to suppress the brake fluid in the first hydraulic circuit from flowing into the second hydraulic circuit.

  On the other hand, when the pressurization state determination unit 124 detects a state where there is no braking request (Y in S262) or there is an accelerator operation (Y in S264), the first hydraulic circuit is not pressurized. Judge that. This indicates that the driver is willing to start the vehicle. If the vehicle is started during the execution of the leakage suppression process, the brake fluid pressure Pfr is applied to the wheel cylinder 23, and therefore brake dragging occurs. Therefore, in such a case, the leakage suppression unit 150 stops the leakage suppression process being executed (S268). That is, by opening the master cut valve 64, the brake pressure of the wheel cylinder 23 is released, and the vehicle can be started smoothly.

  FIG. 19 is a flowchart for explaining another example of the leakage suppression process cancellation process. If the leakage suppression process is not being executed (N in S290), the cancel process is not executed. During the execution of the leakage suppression process (Y in S290), the pressurization state determination unit 124 executes the determination process of the stroke amount of the brake pedal 24 (S292). Specifically, the pressurization state determination unit 124 stores the pedal stroke amount L2 at the time of executing the leakage suppression process in the buffer memory, and the current pedal stroke amount is L2-Lr (Lr is a predetermined amount). It is determined whether L3 (L3 is a predetermined amount) or less is smaller. Here, L3 is a value smaller than L1 described in S118 of FIG.

  For example, L3 = 28 mm and Lr = 15 mm. When the stroke amount L2 at the time of execution of the leakage suppression process is 40 mm, min (L3, L2-Lr) = 25 mm. In this case, when the current stroke amount ST is smaller than 25 mm (Y in S292), the leakage suppression unit 150 stops the leakage suppression process (S294). In the cancellation process shown in FIG. 18, the leakage suppression process is canceled when the braking request is off. However, according to the cancellation process shown in FIG. 19, the leakage suppression process can be canceled before the braking request is turned off. The feeling when the brake pedal 24 is returned can be improved. If the current stroke amount ST is equal to or greater than min (L3, L2-Lr) (N in S292), the leakage suppression process is not stopped. By setting that the pedal stroke amount ST is at most smaller than L3 (L3 <L1) as a condition for stopping the leakage suppression process, it is possible to avoid the occurrence of a situation where re-execution is performed immediately after the leakage suppression process is stopped. There is also an advantage.

  FIG. 20 is a flowchart for explaining still another example of the leakage suppression process cancellation process. If the leakage suppression process is not being executed (N in S310), the cancel process is not executed. During execution of the leakage suppression process (Y in S310), the abnormality determination unit 128 determines whether an output abnormality has occurred in the stroke sensor 25 (S312). If no output abnormality has occurred in the stroke sensor 25 (N in S312), the abnormality determination unit 128 determines whether an output abnormality has occurred in the regulator pressure sensor 71 (S314). When there is no output abnormality in the regulator pressure sensor 71 (N in S314), the abnormality determination unit 128 determines whether an output abnormality has occurred in the control pressure sensor 73 (S316). If no output abnormality has occurred in the control pressure sensor 73 (N in S316), the abnormality determination unit 128 determines whether an output abnormality has occurred in the accumulator pressure sensor 72 (S318). When no output abnormality has occurred in the accumulator pressure sensor 72 (N in S318), the leak suppression unit 150 continues to execute the leak suppression process.

  On the other hand, if an output abnormality has occurred in the stroke sensor 25 (Y in S312), the leak suppression unit 150 stops the leak suppression process (S320). If the stroke sensor 25 fails and an output abnormality occurs, a braking request may be generated even if the brake pedal 24 is not depressed. Since the master cut valve 64 is closed during execution of the leakage suppression process, if an erroneous braking request is generated, a situation may occur in which the master cut valve 64 cannot be opened. Therefore, when an output abnormality occurs in the stroke sensor 25, it is preferable to stop the leakage suppression process and open the master cut valve 64.

  Further, when an output abnormality has occurred in the regulator pressure sensor 71 (Y in S314), an output abnormality has occurred in the control pressure sensor 73 (Y in S316), or an output abnormality has occurred in the accumulator pressure sensor 72 ( (Y in S318), the leakage suppression unit 150 stops the leakage suppression process (S320). Since the outputs of these hydraulic pressure sensors are also used to determine the execution conditions of the leakage suppression process, in order to avoid a situation where the master cut valve 64 is accidentally kept closed when an output abnormality occurs, It is preferable to stop the leakage suppression process and open the master cut valve 64. The function of the abnormality determination unit 128 may be realized by the abnormality detection unit 100 illustrated in FIG.

  FIG. 21 is a flowchart for explaining still another example of the leakage suppression process cancellation process. If the leakage suppression process is not being executed (N in S330), the cancel process is not executed. During execution of the leakage suppression process (Y in S330), the storage amount determination unit 112 monitors the signal from the storage amount decrease detection switch 87 and determines whether the storage amount of the reservoir 34 is normal (S332). When receiving the ON signal, the storage amount determination unit 112 determines that the storage amount of the reservoir 34 is not normal (N in S332). Thereby, the leak suppression part 150 performs a leak suppression process continuously. On the other hand, when receiving the OFF signal, the storage amount determination unit 112 determines that the storage amount is normal (Y in S332). For example, the storage amount of the reservoir 34 can be returned to normal by adding brake fluid. Accordingly, when it is determined that the brake fluid amount in the reservoir 34 is equal to or greater than the reference value specified by the decrease determination line 86, the leakage suppression unit 150 stops the leakage suppression process (S334).

  Note that even if the amount stored in the reservoir 34 returns to normal, air may enter the accumulator 35 and the accumulator pressure Pacc may not be sufficiently increased. Therefore, an example will be shown in which the detection value of the accumulator pressure sensor 72 is used to accurately determine the leakage suppression process stop condition.

  FIG. 22 is a flowchart obtained by improving the cancellation process of the leakage suppression process shown in FIG. If the leakage suppression process is not being executed (N in S330), the cancel process is not executed. During execution of the leakage suppression process (Y in S330), the storage amount determination unit 112 monitors the signal from the storage amount decrease detection switch 87 and determines whether the storage amount of the reservoir 34 is normal (S332). When receiving the ON signal, the storage amount determination unit 112 determines that the storage amount of the reservoir 34 is not normal (N in S332). Thereby, the leak suppression part 150 performs a leak suppression process continuously. On the other hand, when receiving the OFF signal, the storage amount determination unit 112 determines that the storage amount is normal (Y in S332).

  The hydraulic pressure determination unit 122 compares the accumulator pressure Pacc with the predetermined value P7 (S334). If the accumulator pressure Pacc is larger than P7 (Y in S334), the hydraulic pressure determination unit 122 outputs an H value as a comparison result to the buffer memory (S336), and if the accumulator pressure Pacc is equal to or lower than P7, or comparison is not possible. In this case (N in S334), the L value is output to the buffer memory as a comparison result (S338). This comparison is executed at a predetermined cycle, and a comparison result for a predetermined time is held in the buffer memory.

  The hydraulic pressure determination unit 122 refers to the comparison results held in the buffer memory from the latest comparison result to the time Td before, and determines whether the H value is continuously output for the time Td (S340). If all the comparison results are H values, the hydraulic pressure determination unit 122 determines that the state in which the accumulator pressure Pacc is higher than the predetermined value P7 continues for the time Td (Y in S340). On the other hand, if even one L value exists in the comparison result, the hydraulic pressure determination unit 122 determines that the state where the accumulator pressure Pacc is higher than the predetermined value P7 does not continue for the time Td (N in S340). The determination process in S340 is executed every time the comparison process in S334 is performed.

  When the state where Pacc exceeds P7 continues for time Td, the differential pressure determination unit 120 determines whether the differential pressure between Pfr and Prr is equal to or less than P2 (S342). If the differential pressure between Pfr and Prr is greater than P2 (N in S342), the leakage continuation process is continued. On the other hand, if the differential pressure between Pfr and Prr is less than or equal to P2 (Y in S342), not only the accumulator pressure Pacc has recovered to a normal value, but also when the master cut valve 64 is opened, the separation valve 60 is immediately Since it is not self-opening, the leakage suppression unit 150 stops the leakage suppression process (S346).

  The present invention is not limited to the above-described embodiment, and an appropriate combination of the elements of the embodiment is also effective as an embodiment of the present invention. Various modifications such as design changes can be added to the embodiments based on the knowledge of those skilled in the art, and the embodiments to which such modifications are added can be included in the scope of the present invention. .

  For example, although the travel mode determination process has been described with reference to FIG. 14, this determination process is not only used as a condition for executing the leakage suppression process, but also stops the leakage suppression process after the master cut valve 64 is closed. It may be used as a condition.

  The present invention can be used in the field of brake control.

Claims (19)

A first wheel cylinder for applying braking force to the first wheel;
A second wheel cylinder for applying a braking force to a second wheel different from the first wheel;
A first hydraulic circuit for supplying brake fluid from a reservoir to the first wheel cylinder;
A second hydraulic circuit for supplying brake fluid from the reservoir to the second wheel cylinder;
A manual hydraulic pressure source that generates hydraulic pressure according to the amount of brake operation,
A separation valve provided in a main flow path communicating the first hydraulic circuit and the second hydraulic circuit;
An abnormality detection means for detecting an abnormality relating to brake fluid pressure;
Control means for closing the separation valve when an abnormality relating to the brake fluid pressure is detected by the abnormality detection means and the hydraulic pressure generated by the manual hydraulic pressure source is supplied to at least the first hydraulic pressure circuit;
Leakage control means for performing a leakage suppression process for suppressing brake fluid in the first hydraulic circuit from flowing into the second hydraulic circuit after the separation valve is closed by the control means;
Brake control device characterized by comprising   The brake control device according to claim 1, wherein the leakage suppression unit performs a leakage suppression process by closing the control valve.   The brake control device according to claim 2, wherein the control valve is provided in the middle of the reservoir and the separation valve in the first hydraulic circuit.   The brake control device according to any one of claims 1 to 3, wherein the separation valve is a differential pressure valve that opens when a differential pressure before and after the separation valve becomes equal to or greater than a predetermined value P1. First fluid pressure detecting means for detecting a brake fluid pressure of the first hydraulic circuit;
A second fluid pressure detecting means for detecting a brake fluid pressure of the second hydraulic pressure circuit;
The leakage suppression means suppresses leakage when a differential pressure derived from a detection value of the first fluid pressure detection means and a detection value of the second fluid pressure detection means exceeds a predetermined value P2 smaller than a predetermined value P1. The brake control device according to claim 4, wherein processing is executed. First determination means for determining that the amount of brake fluid in the reservoir has decreased below a reference value;
Second fluid pressure detecting means for detecting brake fluid pressure in the second hydraulic pressure circuit or third fluid pressure detecting means for detecting brake fluid pressure in the accumulator flow path;
A second determination means for determining a pressure drop abnormality because the brake fluid pressure of the second hydraulic circuit is lower than a predetermined value P3 or the brake fluid pressure of the accumulator flow path is lower than a predetermined value P4;
Leakage detecting means for detecting leakage of brake fluid to the outside, and
The leak detecting means determines that the first hydraulic pressure circuit determines that the brake fluid amount has decreased below a reference value by the first determining means, and the second hydraulic pressure circuit determines that an abnormal pressure drop has been determined by the second determining means. The brake control device according to any one of claims 1 to 5, wherein leakage of brake fluid to the outside in the vehicle is detected.   The second determination means determines that the state in which the brake fluid pressure in the second hydraulic circuit is lower than the predetermined value P3 continues for a time Ta, or the state in which the brake fluid pressure in the accumulator passage is lower than the predetermined value P4. The brake control device according to claim 6, wherein a pressure drop abnormality is determined from the fact that Tb has continued. The brake control device performs a system check at startup,
Immediately after the end of the system check, the second determination means indicates that the state in which the brake fluid pressure of the second hydraulic circuit is lower than the predetermined value P3 has continued for a time shorter than the time Ta, or the brake fluid pressure in the accumulator flow path. The brake control device according to claim 7, wherein a pressure drop abnormality is determined because a state where the pressure is lower than a predetermined value P4 continues for a time shorter than the time Tb.   The brake according to any one of claims 1 to 8, wherein the leakage suppression means executes a leakage suppression process when a brake fluid pressure of the first hydraulic pressure circuit exceeds a predetermined value P5. Control device.   10. The leak suppression unit temporarily stops the leak suppression process when the brake fluid pressure of the first hydraulic pressure circuit falls below a predetermined value P <b> 6 during execution of the leak suppression process. Brake control device. A pressurization condition determining means for determining a pressurization condition of the first hydraulic circuit;
11. The leakage suppression unit executes a leakage suppression process when it is determined by the pressurization state determination unit that the first hydraulic circuit is in a state of being pressurized. The brake control apparatus in any one of.   12. The brake control apparatus according to claim 11, wherein the pressurization state determination unit determines the pressurization state from an output of a brake pedal stroke detection unit.   13. The brake control according to claim 12, wherein if the pedal stroke amount is determined to exceed a predetermined amount L <b> 1 by the pressurization state determination unit, the leak suppression unit executes a leak suppression process. apparatus.   The leakage suppression unit stops the leakage suppression process being executed when it is determined by the pressurization state determination unit that the first hydraulic circuit is not pressurized. Item 13. The brake control device according to item 11 or 12.   The said pressurization condition determination means memorize | stores the pedal stroke amount L2 at the time of performing a leak suppression process, and the pedal stroke amount is L2-Lr (Lr is a predetermined amount) and predetermined amount L3 (L3 <L1). The brake control device according to claim 13, wherein when the value is smaller than the smaller one, the leakage suppression unit stops the leakage suppression process being executed. An abnormality determining means for determining an output abnormality of a brake pedal stroke detecting means or a brake fluid pressure detecting means;
The brake control device according to any one of claims 1 to 15, wherein when the abnormality determination unit determines an output abnormality, the leakage suppression unit stops the leakage suppression process being executed.   7. The brake according to claim 6, wherein when the first determination unit determines that the brake fluid amount is equal to or greater than a reference value, the leakage suppression unit stops the leakage suppression process being executed. Control device.   18. The brake control device according to claim 17, wherein when the brake fluid pressure in the accumulator channel exceeds a predetermined value P <b> 7, the leakage suppression unit stops the leakage suppression process being executed.   The brake control device according to any one of claims 1 to 18, wherein when the vehicle is being inspected or being maintained, the leakage suppression unit prohibits execution of leakage suppression processing.

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